Just trying to look at this from AY's perspective. It might in fact be true that they have too little business class supply on longhaul flights. Market is changing at least short term as more leisure passengers are buying business class. Business cabins go full day after day while business class fares are higher than in many years. And it must be said that they have given out too many upgrade vouchers.

Which one would you prioritize as AY, upgrade vouchers or high value cash bookings? It's not an easy decision and to be fair I still haven't seen a flight with plenty of space in business class on departure where voucher upgrades haven't been cleared. In this current market predicting demand is difficult too, so IMO it just looks like they are protecting seats for high value cash tickets that are bought close to departure. As evidence they seem to leave the last remaining seat on sale for an astronomical fare instead of clearing an upgrade at T-36. Which is a fair decision in my opinion.